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Message-ID: <a5d9929e0907070859o760fcb16ic88acd0efa3438f3@mail.gmail.com>
Date: Tue, 7 Jul 2009 16:59:18 +0100
From: Joao Correia <joaomiguelcorreia@...il.com>
To: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Cc: LKML <linux-kernel@...r.kernel.org>,
Américo Wang <xiyou.wangcong@...il.com>
Subject: Re: [PATCH 1/3] Increase lockdep limits: MAX_STACK_TRACE_ENTRIES
On Tue, Jul 7, 2009 at 4:55 PM, Peter Zijlstra<a.p.zijlstra@...llo.nl> wrote:
> On Tue, 2009-07-07 at 16:50 +0100, Joao Correia wrote:
>
>> >> Yes. Anything 2.6.31 forward triggers this immediatly during init
>> >> process, at random places.
>> >
>> > Not on my machines it doesn't.. so I suspect its something weird in
>> > your .config or maybe due to some hardware you have that I don't that
>> > triggers different drivers or somesuch.
>>
>> I am not the only one reporting this, and it happens, for example,
>> with a stock .config from a Fedora 11 install.
>>
>> It may, of course, be a funny driver interaction yes, but other than
>> stripping the box piece by piece, how would one go about debugging
>> this otherwise?
>
> One thing to do is stare (or share) at the output
> of /proc/lockdep_chains and see if there's some particularly large
> chains in there, or many of the same name or something.
>
> /proc/lockdep_stats might also be interesting, mine reads like:
>
> [root@...eron ~]# cat /proc/lockdep_stats
> lock-classes: 641 [max: 8191]
> direct dependencies: 3794 [max: 16384]
> indirect dependencies: 7557
> all direct dependencies: 73254
> dependency chains: 3716 [max: 32768]
> dependency chain hlocks: 10167 [max: 163840]
> in-hardirq chains: 21
> in-softirq chains: 353
> in-process chains: 3342
> stack-trace entries: 91035 [max: 262144]
> combined max dependencies: 26035284
> hardirq-safe locks: 28
> hardirq-unsafe locks: 460
> softirq-safe locks: 114
> softirq-unsafe locks: 373
> irq-safe locks: 123
> irq-unsafe locks: 460
> hardirq-read-safe locks: 0
> hardirq-read-unsafe locks: 45
> softirq-read-safe locks: 8
> softirq-read-unsafe locks: 39
> irq-read-safe locks: 8
> irq-read-unsafe locks: 45
> uncategorized locks: 106
> unused locks: 1
> max locking depth: 14
> max recursion depth: 10
> debug_locks: 1
>
>
>
I have definitly much higher numbers than those:
[root@...htech git]# cat /proc/lockdep_stats
lock-classes: 1793 [max: 8191]
direct dependencies: 12032 [max: 16384]
indirect dependencies: 126642
all direct dependencies: 1310382
dependency chains: 28387 [max: 65536]
dependency chain hlocks: 100117 [max: 327680]
in-hardirq chains: 3029
in-softirq chains: 7585
in-process chains: 17773
stack-trace entries: 417613 [max: 1048576]
combined max dependencies: 523805800
hardirq-safe locks: 1074
hardirq-unsafe locks: 575
softirq-safe locks: 1171
softirq-unsafe locks: 445
irq-safe locks: 1184
irq-unsafe locks: 575
hardirq-read-safe locks: 0
hardirq-read-unsafe locks: 68
softirq-read-safe locks: 17
softirq-read-unsafe locks: 55
irq-read-safe locks: 17
irq-read-unsafe locks: 68
uncategorized locks: 103
unused locks: 0
max locking depth: 16
max recursion depth: 11
debug_locks: 1
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